In the construction trades, many distances need to be measured quickly and accurately. These distances include the lengths of lumber to be cut, the internal dimensions of a room, dimensions of objects to be placed in rooms and through doorways, distances from a point to a house, and so on. For many years, the tool of choice for each of these dimensions was the conventional retractable tape measure. As is known, the retractable tape measure includes a tape wound about itself inside a housing that is spring loaded such that when the tape is extended and released, the tape is pulled back within the housing. The tape includes indicia to indicate to the user the distance measured. The tape measure can measure any distance, including the length to which a piece of lumber must be cut.
The tape measure is an excellent tool, but extending the tape over a long distance can be somewhat clumsy and slow. To address this issue, a sonic range finder was developed. In use of this tool, the user points the range finder at a specified target and presses a button. The range finder emits a waveform which is then reflected off the target back to the range finder. The ranger finder calculates the distance from itself to the target by measuring the time it takes for the reflected waveform to return.
The sonic range finder is also an excellent tool, however it is limited in that it can only measure internal dimensions, and not external dimensions. The term internal dimension is used to define a dimension in which at least one of the endpoints includes an inner surface facing the other of the endpoints. The term external dimension, on the other hand, is used to define a dimension in which neither of the endpoints include an inner surface that faces the other of the endpoints.
Thus, the dimension between a first and a second wall is an internal dimension, and the sonic range finder can measure such a dimension quickly and accurately, because the waves can be reflected off either wall. However, the dimensions of a piece of lumber are an external dimension, because there is no surface at the end of the piece of lumber to reflect the waveform. Thus, a sonic range finder cannot measure the length of a piece of lumber or the dimensions of a dresser, for example. Further, the sonic range finder cannot indicate a cut location on a piece of lumber at which point the user needs to cut the lumber to a predetermined length.
Thus, a user must carry both tools to be efficient. In many situations a user will measure the dimensions inside a room, then cut lumber to fit therein. The user first uses the sonic range finder to measure the internal dimensions of the room. The user then puts away the sonic range finder and grasps a tape measure. The user can then measure the lumber to be cut to fit within the room.
While the disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the disclosure to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and the equivalents falling within the spirit and scope of the invention as defined by the appended claims.